This was one thing that really annoyed us when we moved to TN. Practically every house, especially ones that were less than 5 years old (now that would be 15 years) had that set up.
It looked nice when the TV was off, or you were standing walking through the house, but sitting in the sofa it was too high, especially in what they called the hearth room. Instead of having a large family room off the kitchen, it was often a small to medium sized room so your head was even more tilted than if you were farther back away from the screen.
The problem was the furor ace was pretty and adds value to the house, but practically, if you like to watch tv in your “family room” it didn’t make much sense.
Then we moved to the Tampa Bay area, and I was shocked to find new houses with fireplaces! Same situation again. We built our house without one and had our TV at the height I like it.
So, basically, it has a lot to do with wanting the fireplace and the TV in the same visual space where the seating is facing that one focal wall as people said above. Plus, it’s the trend. It’s what builders have been showing.
In modern homes with low sleek fireplaces it works better. Then the TV is at a reasonable height.